Nebulae

The term "nebula" simply means "fuzzy thing." As such, there are many types of nebula observable, and shown in these image pages. Emission nebula typically represent star forming regions, where a few very large, hot stars excite the surrounding gas, making it glow, typically in the red color of hydrogen alpha emission. Reflection nebulae are just that - they are the reflected light of bright stars on interstellar gas and dust. Planetary nebula happen near the end of the life of a star similar to the sun when the outer layers are ejected from a hot core. More details about the different nebula types are included on the individual image pages.